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Re: full thickness blank

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  • Ken Hunter
    ... be ok. I ... Tony, When I cut a blank into two parts I use a horizontally orientated diamond saw blade to make the initial cut as deeply as the diamond saw
    Message 1 of 8 , Feb 1, 2008
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      --- In atm_free@yahoogroups.com, "Tony Gondola" <acgna@...> wrote:
      >
      > Hi Dave,
      >
      > I think if you did it before any other fabrication operation you'd
      be ok. I
      > am kind of curious as to how you'd actually accomplish that task.
      >
      > Tony

      Tony,

      When I cut a blank into two parts I use a horizontally orientated
      diamond saw blade to make the initial cut as deeply as the diamond
      saw blade arbor will let me. In some disks this will complete the
      cut. for disks larger than the diamond saw, the blade will not
      complete the cut and a secondary approach must be used.

      Typically I use a piece of aircraft control cable the same diameter
      as the saw cut already started by the diamond saw. The cable is
      attached to the front of the generating machine and passes over a
      roller that is adjustable in height so that the cable feeds directly
      into the cut as the disk rotates. The cable is routed around the disk
      (in the cut) and again passes over an adjustable roller and down to a
      weight to keep tension on the cable.

      Feed it some carborundum occasionally as it turns and soon you will
      have a "hub" of glass connecting the 2 new disks. When the hub is
      reduced to about a half inch or so, the cable is removed, newsprint
      is placed between the disks (to prevent edge chipping) and one edge
      is hit sharply with the heel of my hand which cleanly breaks the
      connection between the two disks.

      If you carefully adjust the position of the cable and get a clean
      break, you end up with two blanks where you only had one before. You
      do not want to cut completely through with the cable though. I saw a
      blank dragged off the machine once when this happened and it hit the
      floor and broke into several small pieces.

      Ken Hunter
    • ssb73q
      Hi Ken, with the premium that large annealed blanks are more valuable that thin blanks, isn t cutting a blank in half much like turning a large diamond into
      Message 2 of 8 , Feb 1, 2008
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        Hi Ken, with the premium that large annealed blanks are more valuable
        that thin blanks, isn't cutting a blank in half much like turning a
        large diamond into smaller ones?

        Why would one want to do that?

        Regards,
        Richard


        --- In atm_free@yahoogroups.com, "Ken Hunter" <atm_ken_hunter@...>
        wrote:
        >
        > --- In atm_free@yahoogroups.com, "Tony Gondola" <acgna@> wrote:
        > >
        > > Hi Dave,
        > >
        > > I think if you did it before any other fabrication operation
        you'd
        > be ok. I
        > > am kind of curious as to how you'd actually accomplish that task.
        > >
        > > Tony
        >
        > Tony,
        >
        > When I cut a blank into two parts I use a horizontally orientated
        > diamond saw blade to make the initial cut as deeply as the diamond
        > saw blade arbor will let me. In some disks this will complete the
        > cut. for disks larger than the diamond saw, the blade will not
        > complete the cut and a secondary approach must be used.
        >
        > Typically I use a piece of aircraft control cable the same diameter
        > as the saw cut already started by the diamond saw. The cable is
        > attached to the front of the generating machine and passes over a
        > roller that is adjustable in height so that the cable feeds
        directly
        > into the cut as the disk rotates. The cable is routed around the
        disk
        > (in the cut) and again passes over an adjustable roller and down to
        a
        > weight to keep tension on the cable.
        >
        > Feed it some carborundum occasionally as it turns and soon you will
        > have a "hub" of glass connecting the 2 new disks. When the hub is
        > reduced to about a half inch or so, the cable is removed, newsprint
        > is placed between the disks (to prevent edge chipping) and one edge
        > is hit sharply with the heel of my hand which cleanly breaks the
        > connection between the two disks.
        >
        > If you carefully adjust the position of the cable and get a clean
        > break, you end up with two blanks where you only had one before.
        You
        > do not want to cut completely through with the cable though. I saw
        a
        > blank dragged off the machine once when this happened and it hit
        the
        > floor and broke into several small pieces.
        >
        > Ken Hunter
        >
      • zway2bisfancyfree
        ... Tony, I thought of doing something similar to Ken s idea. Start with a blade and put a small grove all the way around the blank, then use steel braided
        Message 3 of 8 , Feb 1, 2008
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          --- In atm_free@yahoogroups.com, "Tony Gondola" <acgna@...> wrote:
          >

          Tony, I thought of doing something similar to Ken's idea. Start
          with a blade and put a small grove all the way around the blank, then
          use steel braided wire with grit and water to continue the process.
          Go very slow to make sure the cut stays on plane.

          If the cable tended to wander then I would leave the blank stationary
          and use a long steel flat thick enough not to flex so I could "saw"
          back and forth with grit applied. It would have to be thick enough
          to stay on plane and more glass would be lost.

          FYI
          Dave



          > Hi Dave,
          >
          > I think if you did it before any other fabrication operation you'd
          be ok. I
          > am kind of curious as to how you'd actually accomplish that task.
          >
          > Tony
          > BigEye Optics
          > http://www.digital-flight.com/thebigeye/optics.htm
          >
          >
          > ----- Original Message -----
          > From: "zway2bisfancyfree" <dmhakenewerth@...>
          > To: <atm_free@yahoogroups.com>
          > Sent: Thursday, January 31, 2008 3:01 PM
          > Subject: [atm_free] full thickness blank
          >
          >
          > >I have a question about an old time full thickness mirror blank.
          If
          > > one had an old 6:1 blank that was fine annealed with good strain
          test
          > > but was 3 inches thick and heavy as a Buick could you slice the
          blank
          > > in half creating two blanks of say 1.65 and 1.25inches or would
          this
          > > ruin the fine anneal?
          > >
          > > Thanks Dave
          > >
          > >
          > >
          > >
          > > Yahoo! Groups Links
          > >
          > >
          > >
          > >
          > >
          > > --
          > > Internal Virus Database is out-of-date.
          > > Checked by AVG Free Edition.
          > > Version: 7.5.516 / Virus Database: 269.19.2/1223 - Release Date:
          1/13/2008
          > > 8:23 PM
          > >
          >
        • Tony Gondola
          It s a lot like the way they cut large blocks in stone quarries these days except they use a diamond cutter cable rather then abrasive. Tony ... From:
          Message 4 of 8 , Feb 1, 2008
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            It's a lot like the way they cut large blocks in stone quarries these days
            except they use a diamond cutter cable rather then abrasive.

            Tony

            ----- Original Message -----
            From: "zway2bisfancyfree" <dmhakenewerth@...>
            To: <atm_free@yahoogroups.com>
            Sent: Friday, February 01, 2008 12:47 PM
            Subject: [atm_free] Re: full thickness blank


            > --- In atm_free@yahoogroups.com, "Tony Gondola" <acgna@...> wrote:
            >>
            >
            > Tony, I thought of doing something similar to Ken's idea. Start
            > with a blade and put a small grove all the way around the blank, then
            > use steel braided wire with grit and water to continue the process.
            > Go very slow to make sure the cut stays on plane.
            >
            > If the cable tended to wander then I would leave the blank stationary
            > and use a long steel flat thick enough not to flex so I could "saw"
            > back and forth with grit applied. It would have to be thick enough
            > to stay on plane and more glass would be lost.
            >
            > FYI
            > Dave
            >
            >
            >
            >> Hi Dave,
            >>
            >> I think if you did it before any other fabrication operation you'd
            > be ok. I
            >> am kind of curious as to how you'd actually accomplish that task.
            >>
            >> Tony
            >> BigEye Optics
            >> http://www.digital-flight.com/thebigeye/optics.htm
            >>
            >>
            >> ----- Original Message -----
            >> From: "zway2bisfancyfree" <dmhakenewerth@...>
            >> To: <atm_free@yahoogroups.com>
            >> Sent: Thursday, January 31, 2008 3:01 PM
            >> Subject: [atm_free] full thickness blank
            >>
            >>
            >> >I have a question about an old time full thickness mirror blank.
            > If
            >> > one had an old 6:1 blank that was fine annealed with good strain
            > test
            >> > but was 3 inches thick and heavy as a Buick could you slice the
            > blank
            >> > in half creating two blanks of say 1.65 and 1.25inches or would
            > this
            >> > ruin the fine anneal?
            >> >
            >> > Thanks Dave
            >> >
            >> >
            >> >
            >> >
            >> > Yahoo! Groups Links
            >> >
            >> >
            >> >
            >> >
            >> >
            >> > --
            >> > Internal Virus Database is out-of-date.
            >> > Checked by AVG Free Edition.
            >> > Version: 7.5.516 / Virus Database: 269.19.2/1223 - Release Date:
            > 1/13/2008
            >> > 8:23 PM
            >> >
            >>
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >
            > --
            > Internal Virus Database is out-of-date.
            > Checked by AVG Free Edition.
            > Version: 7.5.516 / Virus Database: 269.19.2/1223 - Release Date: 1/13/2008
            > 8:23 PM
            >
          • Ken Hunter
            ... Yes... You can sell the BIG diamond once to a limited number of possible customers but smaller diamonds have a greater potential customer base, with likely
            Message 5 of 8 , Feb 3, 2008
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              --- In atm_free@yahoogroups.com, "ssb73q" <ssb73q@...> wrote:
              >
              > Hi Ken, with the premium that large annealed blanks are more valuable
              > that thin blanks, isn't cutting a blank in half much like turning a
              > large diamond into smaller ones?
              >
              > Why would one want to do that?
              >
              > Regards,
              > Richard
              >
              >
              Yes... You can sell the BIG diamond once to a limited number of
              possible customers but smaller diamonds have a greater potential
              customer base, with likely more total profit.

              re: cutting telescope blanks,

              PRO's...
              Thinner blanks weigh less.
              Thinner blanks adjust quicker to temp changes.
              Thinner blanks are less expensive. (2 or 3 for the cost of 1)

              CON's...
              Thinner blanks require more care in mounting.
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